Femto cells are small cellular base stations, typically located at user premises, which provide indoor cellular coverage and rely on the user's broadband connection for backhaul connection to the service provider's network. The backhaul connection to the service provider's network often includes an interface with an IP Multimedia Subsystem (IMS) network for providing multimedia services, for instance using the Session Initiation Protocol (SIP). Thus, in addition to enhancing indoor coverage, a femto cell provides a mobile telephone user with access to cellular voice and data services using the IP-based backhaul.
Femto cells also provide an opportunity for the user to realize service charge savings by replacing the user's landline telephone service with mobile network access. Since most users are more comfortable with using a traditional landline telephone handset while at home or at the office, it is desirable to integrate the mobile handset with the user's landline handsets while using a single telephone number. However, existing femto cell solutions inflexibly prevent the user from employing both mobile and landline handsets for separate and independent communication sessions by either ringing both the mobile and the landline handsets at the same time, requiring the mobile handset to be turned off in order to deliver a ring tone to the landline handsets, or requiring additional equipment, such as a cradle, for manually parking the mobile handset prior to routing the calls to the user's landline handset system. Additionally, many existing femto cell solutions waste network processing resources and increase network signaling traffic by relying on backend processing for controlling the call routing decisions between the mobile and landline handsets.
For instance, U.S. Publication No. 2006/0079236 uses a backend SIP server to determine whether the mobile is currently registered with a fixed or mobile network for purposes of performing call routing, thereby increasing the backhaul connection signaling traffic and requiring additional bandwidth. Once the call is routed to a wireless broadband router via the fixed network, a web interface at a desktop PC is used to manually select whether the mobile or the local handset will ring (or both). Thus, user input is required for call routing among the connected handsets.